Using Locally Adapted Seeds to Restore Native Plants and Arthropods After Plant Invasion and Drought

Non-native plants alter conditions and can reduce the effectiveness of restoration tools. Under these conditions, adding native, locally adapted seeds to favor establishment of native plant communities may provide a potential restoration strategy. We explored the efficacy of soil disturbance and the addition of native seed to restore native plant and arthropod communities in landscapes dominated by Kleberg bluestem (Dichanthium annulatum [Forssk.] Stapf, Old World bluestem grasses, OWB) in summers 2011−2013; our study coincided with severe drought. We compared vegetation and arthropods on disked plots with and without seed (experimental plots), as well as plots within adjacent, undisturbed OWB monocultures. Adding seeds increased cover of native plants and reduced cover of OWBs relative to unseeded plots and undisturbed OWB monocultures. Most of the plants we recorded in seeded plots were not included in the seed mix; we hypothesize that arthropods may have been consuming the added seed rather than the seed bank, permitting native plants in the seed bank to establish. Adding seed also increased arthropod species richness, which was more pronounced as drought severity decreased. During severe drought, arthropod abundance in experimental plots was comparable with undisturbed OWB monocultures, despite the absence of vegetation after disking. However, as drought subsided, undisturbed OWB monocultures had more arthropods than experimental plots. Non-native arthropods, particularly herbivores, were positively associated with OWBs; adding seed was associated with reduced dominance of both OWBs and nonnative arthropods. Reducing dominance of OWBs by adding seed was also associated with reduced dominance of some predators that consume non-native arthropod prey. Understanding how communities respond to multiple disturbances seems especially important to inform restoration strategies given that changes in climate patterns and establishment of invasive species are likely to be more common and widespread.